Global Positioning System integrity channel: a system design analysis

A system design analysis of the GPS integrity channel (GIC), which distributes integrity information to civil aviators equipped with GIC avionics, is presented. The GIC system encompasses ground stations monitoring the integrity of GPS signals-in-space. The information is centrally processed by a master upload station (MUS) where GPS integrity information is generated. A GIC data link is established to carry the GIC information. Reception and processing of the integrity message are performed by the GIC avionics. A proposed GIC system design is analyzed. The study covers a point-to-point communication link starting with the data collection process at the monitoring stations and ending with the integrity message extraction by the GIC avionics. The design uses a star network topology for connecting the ground monitor stations to the MUS with triple redundant transmissions to ensure reliability. Timing analysis has been performed to ensure the feasibility of the design, and it was demonstrated that the proposed system could meet the imposed time-to-alarm limit for different flight phases